The loss of a spouse is the most common severe stressor -- nearly half of us will, necessarily, experience it. Many studies have attempted to measure its psychological effects, and to identify factors, which predict who will cope well with the resulting stress, and who will develop complications. Most of these are unable to reach firm conclusions, however, because they lack prospective data on a population sample prior to the loss. The changing Lives of Older Couples study (CLOC) was designed to overcome this difficulty. A probability sample of 1532 community-dwelling elderly married individuals was evaluated prior to the loss on 685 baseline variables relevant to possible future bereavement, with a subset of 432 subjects evaluated on an additional 410 variables that measured physical and cognitive functioning, and physiological parameters. Bereaved spouses (276 in all) and individually matched controls were evaluated in detail at 6, 18, and 48 months after the loss. This project will use the unique resource of the CLOC dataset to address several specific questions about the stress of losing a spouse. First, we will compare bereaved and non-bereaved matched controls to document, in unprecedented detail, how a variety of psychological, social and physical factors are influenced by bereavement and grief. We will then "unpack" the experience of spousal loss to determine which of its aspects contributes to each of the observed effects. Patterns of variation and subtypes of grief will be defined on the basis of differences in symptoms, severity, and trajectories over time. Finally, and most important, we will use baseline data about the subject, the deceased, the marriage, and the life situation to identify factors that predict variation in the nature of bereavement and its complications. These studies will only begin to tap the wealth of information in the CLOC dataset, so we also plan a considerable investment in preparing the dataset and documentation for dissemination via the web using the protocols, staff and facilities of the Inter-university Consortium for Political and Social Research [CPSR, 1995-1996 #418]. To further this aim, we will also organize a conference that will prepare other investigators to use of the CLOC dataset for additional studies on their own questions. We anticipate that this effort to make the data available to other researchers in a form that they can use will result in significant, and likely unforeseen, advances in our understanding of bereavement.